In an internal combustion engine, such as a diesel engine, carbon and other products from the combustion process can build up on the land of the piston above the upper compression ring. The build-up typically does not form uniformly due to dimensional variations between the piston and the cylinder sleeve, non-uniform heat distribution and secondary motion of the piston. Excessive carbon build up may lead to problems characteristic of current commercial internal combustion engine piston-cylinder assemblies, namely, excessive crevice volume, premature ring fatigue failure, and excessive blow-by of fluids or induced oil combustion. Blow-by or migration of combustion gases or fluid oil past the piston rings is a continuous problem for piston assembly design. Blow-by of combustion gases to the crank case reduces engine compression and robs the engine of its designed power. Therefore, it is necessary and desirable to prevent these potential issues, as well as, remove any carbon and other deposits on a regular basis.
Piston build-up has been dealt with, for example, by increased clearance between the top land of the piston and the cylinder sleeve and reduced oil consumption through refinements in the piston and piston design rings. Additionally, a piston scraping ring helps to scrape the carbon and other deposits that build-up on the top land of the piston. However, the piston scraping ring still has to provide clearance between the ring and the piston to allow for thermal expansion, deformation due to pressure load, the back and forth motion of the piston (piston secondary motion), and the non-uniform heating to the piston.
Thus, there is a need for effective prevention and removal of piston build-up while addressing the potential issues described above. The present device provides a piston scraping ring having a curved or hook shaped feature or groove that may be called the ‘power groove’ for the purposes of this application. While this application specifically describes a piston scraping ring, any other piston ring may be implemented to add the power groove feature. This feature or groove causes a combustion pressure wave to expand and reverse direction when the combustion pressure wave has impact with the feature. This impacted wave further acts against the following oncoming pressure wave resulting from combustion and so on, thereby reducing the pressure experienced by the piston rings. The reduction in pressure on the piston rings reduces the wear between the piston rings and the cylinder sleeve. Through this pressure reduction, the power groove additionally improves the sealing capability of the piston rings by reducing blow-by, which in turn, improves the engine efficiency. The present device reduces carbon and other build-up, facilitates removal of carbon and other deposits on the top land of the piston, and lowers pressure on the piston rings.